The present invention relates to laminated electronic devices and a method of manufacturing the same, and more particularly to the structure of through conductors (throughhole conductors) which are suitable for application to laminated electronic devices including resonators such as filters.
A variety of laminated electronic devices have been provided. Such laminated electronic devices have a variety of functions implemented by circuits formed of internal conductors of laminates which include a plurality of wiring layers. For example, a laminated filter which comprises a resonator in an internal wiring layer of a ceramic laminate performs functions of selecting a frequency and removing unwanted waves in high-frequency radio communication systems such as a mobile phone, a wireless LAN, Bluetooth®, WiMAX™, and the like, and constitutes one of main components in these communication systems.
Laminates may be implemented, for example, by ceramic laminates which are advantageous in achieving a smaller size and a higher integration. In manufacturing a laminate, conductor patterns are formed on surfaces of a plurality of ceramic green sheets, which are then stacked one on another and bonded with one another with heat and pressure. The resulting product is next cut into chips which are then sintered, thus completing laminates. Here, through conductors (throughhole conductors) extending vertically (in the laminating direction) through insulating layers are generally employed for electrically interconnecting electrodes which are arranged on different wiring layers within a laminate.
Such throughhole conductors are disclosed, for example, in JP-A-2-134889 and JP-A-4-105393.